Patent GB-891011-A (GB)
Title: Proportional spacing typewriter
IPC: B41J19/58
Filed: 1959-07-01
Abstract: 891,011. Typewriters &c. SPERRY RAND CORPORATION. July 1, 1959 [Oct. 2, 1958], No. 22599/59. Class 100(4) The variable letter spacing movements are controlled by stop arms 49 to 51, Fig. 4, set by actuation of the type bar bell-cranks 19 which act through bell-crank levers 34 and slides 30 to pivot appropriate permutation bails 39 to 44 which by an upper or lower arm 52, 53 engage an actuator 57 to 59 to raise its corresponding stop arm 49 to 51 to give the desired letter spacing. The stop arms 49 to 51 give two to four spacing movements, respectively, while a five increment movement results if no arm is moved. Each slide 30 moves two bails 39 to 44 but only one is effective to move an actuator 57 to 59 since the case shift mechanism pivots a bracket 66 to cause one or other of the arms 52, 53 to be effective for the upper or lower case position respectively. Escapement occurs when a universal bar causes pivoting of a rocker 77, Fig. 8, which causes a pawl 93 to engage the escapement gear 92 and withdraws a segment 81 which is pivoted by a spring 84 until its pin 79 is arrested by any moved stop arm 49 to 51 so that when the rocker 77 is pivoted back an escapement of appropriate length occurs. The effective spacing can be extended or contracted one increment by a key which causes a pin engaging a slot 94 in the ends of the stop arms 49 to 51 to move them together so that each is effective to give one more or one less increment of spacing than normal. This mechanism is also used by two and three increments spacing bars which are provided and which by power means actuates slides similar to 30 to give the appropriate spacing. Back spacing is effected by power through a pawl 133, Fig. 15, which turns the gear 92 back a single increment on actuation of an arm 131 or repeat actuation can be effected by the power mechanism on further depression of a key as described in U.S.A. Specification 2,714,948. The sector 81 acts as a detent during back spacing being held against retraction by a finger 137 of a bail 134 engaging its pin 79 when as the arm 131 rises to cause back spacing its pin 139 allows a spring 140 to pivot the bail 134. Sound deadening on carriage return and the rebound preventing is effected by an arm 144, Fig. 8, urged counter-clockwise by a spring 146 which contracts about a hub 147 of the escapement gear 92 as it rotates during carriage return. The arm 144 contacts the pin 79 forcing it against and along a dog 148 to disengage the segment 81 from the wheel 92. A bell-crank 153 fitted over a pin 155 on the arm 144 is thus moved and held pivoted counter-clockwise. On completion of carriage return a fixed stop 163 on a control shaft 159 is engaged by an adjustable margin stop 161 and the shaft 159 is moved to the left, Fig. 8, against yielding mechanism so that a cam 164 swings a plate 166 to tension a spring 168 which tends to pull down a slide detent 169 an extension 173 of which thus engages a pin 174 on the segment carrier 83 to apply pressure tending to re-engage the segment 81 with the gear 92. As the carriage rebounds the tensioning of a spring 168 aids a spring 88 in re-engaging segment 81 but a cam 158 prevents this, and restoration of the bell-crank 153, until the correct position is reached. The spring 168 provides extra force so that the spring 88 can be weak enough for normal operation. Movement of the shaft 159 is also used to disengage the clutch to the carriage return belt after the carriage has come to rest at the left margin stop. The usual finger latch withdraws the segment 81 to prevent noise when the carriage is moved manually. Tabulation is effected by usual tabulation stop mechanism and to prevent movement of the segment 81 a tabulator extension 183, Fig. 21, engages a detent 180 to force it into the hooked end 186 of the segment 81 to hold it during tabulation movement on completion of which the extension 183 rises, after a segment 81 has reengaged the gear 92, to allow a spring 188 to withdraw the detent. A rebound mechanism catch is also provided. U.S.A. Specifications 2,289,531, 2,304,216, 2,326,312, 2,638,199, 2,919,007 and 2,930,471 are referred to.